Temperature compensation for a fiber-Bragg-grating-based magnetostrictive sensor

We demonstrate two simple techniques for the compensation of the temperature effects in a fiber-Bragg-grating-based magnetostrictive sensor. These techniques are based on using two specially mounted fiber Bragg gratings (FBGs). In one technique, the two FBGs, perpendicular to each other, are bonded onto a single magnetostrictive plate, while in the other technique, they are bonded onto two different magnetostrictive bars that possess close thermal coefficients of opposite expansion coefficients and magnetostrictive signs. In both cases, the Bragg wavelength difference between the two FBGs is insensitive to the temperature and measures the sum of the magnetostrictive effects experienced by the two gratings. Using these techniques, we have been able to reduce the temperature sensitivity of the sensor by more than 10 times. (C) 2003 Wiley Periodicals, Inc.